linux.git/arch/mips/kernel/elf.c, branch v6.12.80

MIPS: Implement ieee754 NAN2008 emulation mode

2024-07-12T11:09:25+00:00

Implement ieee754 NAN2008 emulation mode.

When this mode is enabled, kernel will accept ELF file
compiled for both NaN 2008 and NaN legacy, but if hardware
does not have capability to match ELF's NaN mode, __own_fpu
will fail for corresponding thread and fpuemu will then kick
in.

This mode trade performance for correctness, while maintaining
support for both NaN mode regardless of hardware capability.
It is useful for multilib installation that have both types
of binary exist in system.

Reviewed-by: Philippe Mathieu-Daudé 
Signed-off-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer

mips: Call lose_fpu(0) before initializing fcr31 in mips_set_personality_nan

2024-01-27T10:08:04+00:00

If we still own the FPU after initializing fcr31, when we are preempted
the dirty value in the FPU will be read out and stored into fcr31,
clobbering our setting.  This can cause an improper floating-point
environment after execve().  For example:

    zsh% cat measure.c
    #include 
    int main() { return fetestexcept(FE_INEXACT); }
    zsh% cc measure.c -o measure -lm
    zsh% echo $((1.0/3)) # raising FE_INEXACT
    0.33333333333333331
    zsh% while ./measure; do ; done
    (stopped in seconds)

Call lose_fpu(0) before setting fcr31 to prevent this.

Closes: https://lore.kernel.org/linux-mips/7a6aa1bbdbbe2e63ae96ff163fab0349f58f1b9e.camel@xry111.site/
Fixes: 9b26616c8d9d ("MIPS: Respect the ISA level in FCSR handling")
Cc: stable@vger.kernel.org
Signed-off-by: Xi Ruoyao 
Signed-off-by: Thomas Bogendoerfer

MIPS: Modernize READ_IMPLIES_EXEC

2022-02-23T12:08:30+00:00

I'm doing some thread necromancy of
https://lore.kernel.org/lkml/202007081624.82FA0CC1EA@keescook/

x86, arm64, and arm32 adjusted their READ_IMPLIES_EXEC logic to better
align with the safer defaults and the interactions with other mappings,
which I illustrated with this comment on x86:

/*
 * An executable for which elf_read_implies_exec() returns TRUE will
 * have the READ_IMPLIES_EXEC personality flag set automatically.
 *
 * The decision process for determining the results are:
 *
 *                 CPU: | lacks NX*  | has NX, ia32     | has NX, x86_64 |
 * ELF:                 |            |                  |                |
 * ---------------------|------------|------------------|----------------|
 * missing PT_GNU_STACK | exec-all   | exec-all         | exec-none      |
 * PT_GNU_STACK == RWX  | exec-stack | exec-stack       | exec-stack     |
 * PT_GNU_STACK == RW   | exec-none  | exec-none        | exec-none      |
 *
 *  exec-all  : all PROT_READ user mappings are executable, except when
 *              backed by files on a noexec-filesystem.
 *  exec-none : only PROT_EXEC user mappings are executable.
 *  exec-stack: only the stack and PROT_EXEC user mappings are
 *  executable.
 *
 *  *this column has no architectural effect: NX markings are ignored by
 *   hardware, but may have behavioral effects when "wants X" collides with
 *   "cannot be X" constraints in memory permission flags, as in
 *   https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com
 *
 */

For MIPS, the "lacks NX" above is the "!cpu_has_rixi" check. On x86,
we decided that the READ_IMPLIES_EXEC flag needed to reflect the
expectations, not the architectural behavior due to bad interactions
as noted above, as always returning "1" on non-NX hardware breaks
some mappings.

The other part of the issue is "what does the MIPS toolchain do for
PT_GNU_STACK?" The answer seems to be "by default, include PT_GNU_STACK,
but mark it executable" (likely due to concerns over non-NX hardware):

$ mipsel-linux-gnu-gcc -o hello_world hello_world.c
$ llvm-readelf -lW hellow_world | grep GNU_STACK
  GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x10

Given that older hardware doesn't support non-executable memory, it
seems safe to make the "PT_GNU_STACK is absent" logic mean "assume
non-executable", but this might break very old software running on
modern MIPS. This situation matches the ia32-on-x86_64 logic x86
uses (which assumes needing READ_IMPLIES_EXEC in that situation). But
modern toolchains on modern MIPS hardware should follow a safer default
(assume NX stack).

A follow-up to this change would be to switch the MIPS toolchain to emit
a non-executable PT_GNU_STACK, as this seems to be unneeded.

Cc: Thomas Bogendoerfer 
Cc: Tiezhu Yang 
Cc: Xuefeng Li 
Cc: Juxin Gao 
Cc: linux-mips@vger.kernel.org
Signed-off-by: Kees Cook 
Signed-off-by: Thomas Bogendoerfer

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

MIPS: Avoid FP ELF checks when CONFIG_MIPS_FP_SUPPORT=n

2018-11-09T18:23:18+00:00

When CONFIG_MIPS_FP_SUPPORT=n we don't support floating point, so we can
avoid needless checks of ELF headers specifying the FP ABI or NaN
encoding to use. Deselect CONFIG_ARCH_BINFMT_ELF_STATE in this case to
avoid the need for our arch_elf_pt_proc() & arch_check_elf() functions,
and stub out the mips_set_personality_nan() & mips_set_personality_fp()
functions such that SET_PERSONALITY() doesn't need to worry about any of
this.

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/21011/
Cc: linux-mips@linux-mips.org

Update MIPS email addresses

2017-11-03T16:02:30+00:00

MIPS will soon not be a part of Imagination Technologies, and as such
many @imgtec.com email addresses will no longer be valid. This patch
updates the addresses for those who:

 - Have 10 or more patches in mainline authored using an @imgtec.com
   email address, or any patches dated within the past year.

 - Are still with Imagination but leaving as part of the MIPS business
   unit, as determined from an internal email address list.

 - Haven't already updated their email address (ie. JamesH) or expressed
   a desire to be excluded (ie. Maciej).

 - Acked v2 or earlier of this patch, which leaves Deng-Cheng, Matt &
   myself.

New addresses are of the form firstname.lastname@mips.com, and all
verified against an internal email address list.  An entry is added to
.mailmap for each person such that get_maintainer.pl will report the new
addresses rather than @imgtec.com addresses which will soon be dead.

Instances of the affected addresses throughout the tree are then
mechanically replaced with the new @mips.com address.

Signed-off-by: Paul Burton 
Cc: Deng-Cheng Zhu 
Cc: Deng-Cheng Zhu 
Acked-by: Dengcheng Zhu 
Cc: Matt Redfearn 
Cc: Matt Redfearn 
Acked-by: Matt Redfearn 
Cc: Andrew Morton 
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: trivial@kernel.org
Signed-off-by: Linus Torvalds

fs: fix kernel_read prototype

2017-09-04T23:05:15+00:00

Use proper ssize_t and size_t types for the return value and count
argument, move the offset last and make it an in/out argument like
all other read/write helpers, and make the buf argument a void pointer
to get rid of lots of casts in the callers.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

MIPS: Avoid BUG warning in arch_check_elf

2017-04-12T13:22:13+00:00

arch_check_elf contains a usage of current_cpu_data that will call
smp_processor_id() with preemption enabled and therefore triggers a
"BUG: using smp_processor_id() in preemptible" warning when an fpxx
executable is loaded.

As a follow-up to commit b244614a60ab ("MIPS: Avoid a BUG warning during
prctl(PR_SET_FP_MODE, ...)"), apply the same fix to arch_check_elf by
using raw_current_cpu_data instead. The rationale quoted from the previous
commit:

"It is assumed throughout the kernel that if any CPU has an FPU, then
all CPUs would have an FPU as well, so it is safe to perform the check
with preemption enabled - change the code to use raw_ variant of the
check to avoid the warning."

Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
Signed-off-by: James Cowgill 
CC:  # 4.0+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15951/
Signed-off-by: Ralf Baechle

Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

2016-08-06T13:13:11+00:00

Pull MIPS updates from Ralf Baechle:
 "This is the main pull request for MIPS for 4.8.  Also includes is a
  minor SSB cleanup as SSB code traditionally is merged through the MIPS
  tree:

  ATH25:
    - MIPS: Add default configuration for ath25

  Boot:
    - For zboot, copy appended dtb to the end of the kernel
    - store the appended dtb address in a variable

  BPF:
    - Fix off by one error in offset allocation

  Cobalt code:
    - Fix typos

  Core code:
    - debugfs_create_file returns NULL on error, so don't use IS_ERR for
      testing for errors.
    - Fix double locking issue in RM7000 S-cache code.  This would only
      affect RM7000 ARC systems on reboot.
    - Fix page table corruption on THP permission changes.
    - Use compat_sys_keyctl for 32 bit userspace on 64 bit kernels.
      David says, there are no compatibility issues raised by this fix.
    - Move some signal code around.
    - Rewrite r4k count/compare clockevent device registration such that
      min_delta_ticks/max_delta_ticks files are guaranteed to be
      initialized.
    - Only register r4k count/compare as clockevent device if we can
      assume the clock to be constant.
    - Fix MSA asm warnings in control reg accessors
    - uasm and tlbex fixes and tweaking.
    - Print segment physical address when EU=1.
    - Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO.
    - CP: Allow booting by VP other than VP 0
    - Cache handling fixes and optimizations for r4k class caches
    - Add hotplug support for R6 processors
    - Cleanup hotplug bits in kconfig
    - traps: return correct si code for accessing nonmapped addresses
    - Remove cpu_has_safe_index_cacheops

  Lantiq:
    - Register IRQ handler for virtual IRQ number
    - Fix EIU interrupt loading code
    - Use the real EXIN count
    - Fix build error.

  Loongson 3:
    - Increase HPET_MIN_PROG_DELTA and decrease HPET_MIN_CYCLES

  Octeon:
    - Delete built-in DTB pruning code for D-Link DSR-1000N.
    - Clean up GPIO definitions in dlink_dsr-1000n.dts.
    - Add more LEDs to the DSR-100n DTS
    - Fix off by one in octeon_irq_gpio_map()
    - Typo fixes
    - Enable SATA by default in cavium_octeon_defconfig
    - Support readq/writeq()
    - Remove forced mappings of USB interrupts.
    - Ensure DMA descriptors are always in the low 4GB
    - Improve USB reset code for OCTEON II.

  Pistachio:
    - Add maintainers entry for pistachio SoC Support
    - Remove plat_setup_iocoherency

  Ralink:
    - Fix pwm UART in spis group pinmux.

  SSB:
    - Change bare unsigned to unsigned int to suit coding style

  Tools:
    - Fix reloc tool compiler warnings.

  Other:
    - Delete use of ARCH_WANT_OPTIONAL_GPIOLIB"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (61 commits)
  MIPS: mm: Fix definition of R6 cache instruction
  MIPS: tools: Fix relocs tool compiler warnings
  MIPS: Cobalt: Fix typo
  MIPS: Octeon: Fix typo
  MIPS: Lantiq: Fix build failure
  MIPS: Use CPHYSADDR to implement mips32 __pa
  MIPS: Octeon: Dlink_dsr-1000n.dts: add more leds.
  MIPS: Octeon: Clean up GPIO definitions in dlink_dsr-1000n.dts.
  MIPS: Octeon: Delete built-in DTB pruning code for D-Link DSR-1000N.
  MIPS: store the appended dtb address in a variable
  MIPS: ZBOOT: copy appended dtb to the end of the kernel
  MIPS: ralink: fix spis group pinmux
  MIPS: Factor o32 specific code into signal_o32.c
  MIPS: non-exec stack & heap when non-exec PT_GNU_STACK is present
  MIPS: Use per-mm page to execute branch delay slot instructions
  MIPS: Modify error handling
  MIPS: c-r4k: Use SMP calls for CM indexed cache ops
  MIPS: c-r4k: Avoid small flush_icache_range SMP calls
  MIPS: c-r4k: Local flush_icache_range cache op override
  MIPS: c-r4k: Split r4k_flush_kernel_vmap_range()
  ...

tree-wide: replace config_enabled() with IS_ENABLED()

2016-08-04T12:50:07+00:00

The use of config_enabled() against config options is ambiguous.  In
practical terms, config_enabled() is equivalent to IS_BUILTIN(), but the
author might have used it for the meaning of IS_ENABLED().  Using
IS_ENABLED(), IS_BUILTIN(), IS_MODULE() etc.  makes the intention
clearer.

This commit replaces config_enabled() with IS_ENABLED() where possible.
This commit is only touching bool config options.

I noticed two cases where config_enabled() is used against a tristate
option:

 - config_enabled(CONFIG_HWMON)
  [ drivers/net/wireless/ath/ath10k/thermal.c ]

 - config_enabled(CONFIG_BACKLIGHT_CLASS_DEVICE)
  [ drivers/gpu/drm/gma500/opregion.c ]

I did not touch them because they should be converted to IS_BUILTIN()
in order to keep the logic, but I was not sure it was the authors'
intention.

Link: http://lkml.kernel.org/r/1465215656-20569-1-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada 
Acked-by: Kees Cook 
Cc: Stas Sergeev 
Cc: Matt Redfearn 
Cc: Joshua Kinard 
Cc: Jiri Slaby 
Cc: Bjorn Helgaas 
Cc: Borislav Petkov 
Cc: Markos Chandras 
Cc: "Dmitry V. Levin" 
Cc: yu-cheng yu 
Cc: James Hogan 
Cc: Brian Gerst 
Cc: Johannes Berg 
Cc: Peter Zijlstra 
Cc: Al Viro 
Cc: Will Drewry 
Cc: Nikolay Martynov 
Cc: Huacai Chen 
Cc: "H. Peter Anvin" 
Cc: Thomas Gleixner 
Cc: Daniel Borkmann 
Cc: Leonid Yegoshin 
Cc: Rafal Milecki 
Cc: James Cowgill 
Cc: Greg Kroah-Hartman 
Cc: Ralf Baechle 
Cc: Alex Smith 
Cc: Adam Buchbinder 
Cc: Qais Yousef 
Cc: Jiang Liu 
Cc: Mikko Rapeli 
Cc: Paul Gortmaker 
Cc: Denys Vlasenko 
Cc: Brian Norris 
Cc: Hidehiro Kawai 
Cc: "Luis R. Rodriguez" 
Cc: Andy Lutomirski 
Cc: Ingo Molnar 
Cc: Dave Hansen 
Cc: "Kirill A. Shutemov" 
Cc: Roland McGrath 
Cc: Paul Burton 
Cc: Kalle Valo 
Cc: Viresh Kumar 
Cc: Tony Wu 
Cc: Huaitong Han 
Cc: Sumit Semwal 
Cc: Alexei Starovoitov 
Cc: Juergen Gross 
Cc: Jason Cooper 
Cc: "David S. Miller" 
Cc: Oleg Nesterov 
Cc: Andrea Gelmini 
Cc: David Woodhouse 
Cc: Marc Zyngier 
Cc: Rabin Vincent 
Cc: "Maciej W. Rozycki" 
Cc: David Daney 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds